Soft copper wire : 18 gauge ( wire diameter 1mm ) : 18cm ( 7 inch) (You should use 19-20cm to avoid missing wire) 20 gauge ( ...

Soft copper wire : 20 gauge ( wire diameter 0.8mm ) : 3cm ( 1,2 inch) for each herringbone link 2cm ( 0.8 inch) for clasp 28 ...